1. Field of the Invention
The present invention relates to a switch covering device and, in particular, to a semi-elastic switch covering device for use in an electrical system such as a display monitor having an external control panel. More specifically, the invention relates to a control apparatus in which malfunction is prevented by locating a gap-maintaining member between a control knob and a tactile switch so as to maintain a constant gap between the control knob and the tactile switch when the control knob is not being activated.
2. Background Art
Many electrical systems, e.g., a display monitor, television, or printer, make use of an external control panel to allow the user to manipulate the various functions made available by the electrical system. Typically, these control panels are positioned opposite from pressure switches that are installed inside the outer housing of the electrical system and activated by the indirect contact of a button installed in the outer housing. The pressure switch is mounted on a main board and aligned with an external control button so that a user activates the switch by pressing on the button. Examples of this are shown in U.S. Pat. No. 5,363,150 to Kojima entitled Casing for a Television Set, U.S. Pat. No. 5,623,393 to Yau entitled Monitor Control Panel Mounting Structure, and U.S. Pat. No. 5,347,427 to Kinoshita entitled Cabinet Assembly.
Furthermore, some electrical systems use spacers to support the main board and maintain the required design distance between the outer control button and the pressure switch. I have observed that these spacers create tolerance problems due to naturally occurring deformations in the panel due to cyclic stresses that accumulate with frequent use over time and manufacturing variations in the assembled components. When the actual distance between the outer control button and the pressure switch is greater than the design distance the user may experience difficulty in activating the pressure switch by pressing the button. When the actual distance is less than the design distance the user may find that the pressure switch is continuously activated or activated too easily. I expect that an intermediary device that could maintain the constant design spacing would increase that reliability of and simplify the manufacture of control panels for typical electrical systems.
Thus, in prior arrangements, a gap between a control button or knob and a pressure or tactile switch varies in dependence on the deformation of the apparatus and on the variation in the manufacturing tolerance limit of the apparatus. This variation in the gap between the control button or knob and the pressure or tactile switch causes the switch to malfunction due to inadvertent contact between the button or knob and the switch without any action on the part of the user. Therefore, there is a need in the prior art for the development of a control apparatus having some means or technique for maintaining a constant gap between a control button or knob and a pressure or tactile switch.
Accordingly, it is an object of the present invention to provide a switch covering device that is positioned between a switch and a control button.
It is another object to provide a switch covering device that improves the performance of the control panel.
It is still another object to provide a switch covering device that enhances the system reliability of a control panel by preventing malfunctions due to deformations resulting from cyclic stress from repetitive use.
It is yet another object to provide a switch covering device that can compensate for inherent physical tolerances of various components of the electrical system and housing.
It is still yet another object to provide a switch covering device that maintains a precise interval between the pressure switch and the associated member that activates the switch.
It is a further object to provide a switch covering device that can be adjusted to compensate for deformations of system components that occur over time.
It is a further object to provide a control apparatus in which there is a constant gap between a control button or knob and a pressure or tactile switch.
It is a further object to provide a control apparatus in which variation in the gap between the control button or knob and the pressure or tactile switch is prevented.
It is a still further object to provide a control apparatus having a gap-maintaining member disposed between a control knob or button and a pressure or tactile switch.
To achieve these and other objects, in a first embodiment of the invention, a semi-elastic switch structure is attached to the frame of an electrical system between a pressure switch and the external control panel. This structure may be constructed of a basically rigid material except for the switch covers that are constructed of an elastic material that allows the covers to be depressed by a button and brought into contact with a pressure switch. This semi-elastic switch structure covers the pressure switches and may be attached to the main board or frame of the electrical system by a plurality of connectors, flexible supports, and latching members. The main board supports and connects the pressure switches to the electrical system.
This semi-elastic switch structure creates a third potential space, other than the constant space between the control button and the switch cover and the constant space between the switch cover and the pressure switch. This extra space can be formed between the underside of the latching members and the frame. This enables the constant space between the button and the switch cover and the constant space between the switch cover and the pressure switch to be adjusted to compensate for tolerance errors in the manufacture of other components during the manufacturing process or the deformation of components due to repetitive use.
To further achieve the above and other objects of the invention, in a second embodiment of the invention, a control apparatus for an electronic machine comprises: a case having a knob hole; a control knob disposed in the knob hole and having a plurality of bosses; a gap-maintaining member having a plurality of latches corresponding to a plurality of latch holes in a main board and a plurality of elastic tactile members corresponding to protrusions; and a main board including a plurality of tactile switches engaged with corresponding elastic tactile members.
Furthermore, in the second embodiment of the invention, the main board is located on an is opposite side of the knob relative to the gap-maintaining member. A plurality of main board holders for latching the main board to the gap-maintaining member is provided. The gap-maintaining member is attached to a frame inside the electronic machine by latching a latch of the gap-maintaining member into a latch hole formed on a frame. The tactile switch is disposed on the main board, which is attached to the gap-maintaining member, and maintains a constant gap between the tactile switch and the elastic tactile member of the gap-maintaining member. The elastic tactile member maintains a second gap between the protrusion of the knob and the elastic tactile member constant.